Late stage reprojection

ABSTRACT

Methods for generating and displaying images associated with one or more virtual objects within an augmented reality environment at a frame rate that is greater than a rendering frame rate are described. The rendering frame rate may correspond with the minimum time to render images associated with a pose of a head-mounted display device (HMD). In some embodiments, the HMD may determine a predicted pose associated with a future position and orientation of the HMD, generate a pre-rendered image based on the predicted pose, determine an updated pose associated with the HMD subsequent to generating the pre-rendered image, generate an updated image based on the updated pose and the pre-rendered image, and display the updated image on the HMD. The updated image may be generated via a homographic transformation and/or a pixel offset adjustment of the pre-rendered image.

BACKGROUND

Augmented reality (AR) relates to providing an augmented real-worldenvironment where the perception of a real-world environment (or datarepresenting a real-world environment) is augmented or modified withcomputer-generated virtual data. For example, data representing areal-world environment may be captured in real-time using sensory inputdevices such as a camera or microphone and augmented withcomputer-generated virtual data including virtual images and virtualsounds. The virtual data may also include information related to thereal-world environment such as a text description associated with areal-world object in the real-world environment. The objects within anAR environment may include real objects (i.e., objects that exist withina particular real-world environment) and virtual objects (i.e., objectsthat do not exist within the particular real-world environment).

In order to realistically integrate virtual objects into an ARenvironment, an AR system typically performs several tasks includingmapping and localization. Mapping relates to the process of generating amap of a real-world environment. Localization relates to the process oflocating a particular point of view or pose relative to the map of thereal-world environment. In some cases, an AR system may localize thepose of a mobile device moving within a real-world environment inreal-time in order to determine the particular pose associated with themobile device that needs to be augmented as the mobile device moveswithin the real-world environment.

An AR environment may be provided to an end user of a mobile deviceusing an electronic display (e.g., an LED display integrated with ahead-mounted display device). The electronic display may display imagesof virtual objects to the end user by modulating light provided to theelectronic display (e.g., a liquid crystal on silicon display) or bygenerating light within the electronic display (e.g., an OLED display).An OLED, or organic light emitting diode, is an LED in which theemissive electroluminescent layer comprises an organic film. An OLEDdisplay may comprise a passive matrix OLED display or an active matrixOLED display. An active matrix OLED display uses one or more thin-filmtransistors (TFTs) within each OLED pixel for controlling the amount oflight generated per pixel. In one example, each OLED pixel may comprisea first TFT for driving an OLED and a second TFT for latching data forcontrolling the first TFT. The TFTs may comprise polysilicon TFTs oramorphous silicon TFTs. In some cases, an OLED display may comprisegroups of red, green, and blue emitting sub-pixels (i.e., each of theOLED pixels may comprise a plurality of LEDs for generating red, green,and blue light). An OLED display may also comprise groups of cyan,yellow, magenta, and white emitting sub-pixels.

SUMMARY

Technology is described for generating and projecting images associatedwith one or more virtual objects within an augmented reality (AR)environment at a frame rate that is greater than a rendering frame rate.The rendering frame rate may correspond with the minimum time to renderimages associated with a particular pose of a head-mounted displaydevice (HMD). In some embodiments, the HMD may determine a predictedpose associated with a future position and orientation of the HMD (e.g.,a predicted pose of the HMD 8 ms or 16 ms in the future), generate apre-rendered image based on the predicted pose, determine an updatedpose associated with the HMD subsequent to generating the pre-renderedimage, generate an updated image based on the updated pose and thepre-rendered image, and display the updated image on the HMD. Theupdated image may be generated via a homographic transformation and/or apixel offset adjustment of the pre-rendered image.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of one embodiment of a networked computingenvironment in which the disclosed technology may be practiced.

FIG. 2A depicts one embodiment of a mobile device in communication witha second mobile device.

FIG. 2B depicts one embodiment of a portion of an HMD.

FIG. 3A depicts one embodiment of a system for generating and displayingimages associated with a virtual object at a frame rate that is greaterthan a rendering frame rate for a core rendering pipeline.

FIG. 3B depicts one embodiment of a display.

FIG. 3C depicts an alternative embodiment of a display.

FIG. 4A depicts one embodiment of a portion of a pre-rendered image andan updated image based on the pre-rendered image.

FIG. 4B depicts one embodiment of a pre-rendered image and samplingregions used for generating updated images (or target images).

FIG. 4C depicts one embodiment of the a pre-rendered image and theapplication of a rolling buffer to the pre-rendered image.

FIG. 5A depicts one embodiment of applying late stage graphicaladjustments to a rendered image in order to generate updated images.

FIG. 5B depicts one embodiment of a display sequence associated with adisplay.

FIG. 5C depicts an alternative embodiment of a display sequenceassociated with a display.

FIG. 6A is a flowchart describing one embodiment of a method forgenerating and displaying images associated with virtual objects at aframe rate that is greater than a rendering frame rate.

FIG. 6B is a flowchart describing one embodiment of a method for makinggraphical adjustments to rendered images provided to a display usingcircuitry integrated with the display.

FIG. 7A is a flowchart describing an alternative embodiment of a methodfor generating and displaying images associated with virtual objects ata frame rate that is greater than a rendering frame rate.

FIG. 7B is a flowchart describing one embodiment of a process forgenerating a rendered image.

FIG. 8 is a block diagram of one embodiment of a mobile device.

DETAILED DESCRIPTION

Technology is described for generating and displaying images associatedwith one or more virtual objects within an augmented reality (AR)environment at a frame rate that is greater than a rendering frame rateand for improving virtual object stability. The displayed images mayinclude late stage graphical adjustments of pre-rendered scenes (i.e.,forward predicted scenes that are rendered at the rendering frame rate)in order to incorporate higher frequency pose estimates. The renderingframe rate may correspond with the minimum time to render imagesassociated with a pose of a head-mounted display device (HMD). In someembodiments, the HMD may determine a predicted pose associated with afuture position and orientation of the HMD (e.g., a predicted pose ofthe HMD 10 ms or 20 ms in the future), generate a pre-rendered imagebased on the predicted pose, determine an updated pose associated withthe HMD subsequent to generating the pre-rendered image or concurrentwith the pre-rendered image being generated, generate an updated imagebased on the updated pose and the pre-rendered image, and display theupdated image on the HMD. The updated image may be generated via ahomographic transformation and/or a pixel offset adjustment of thepre-rendered image. In some cases, the updated image may be generated bycircuitry within the display.

In some embodiments, the predicted pose may be determined based on acurrent position and orientation of the HMD and an acceleration and avelocity of the HMD immediately prior to determining the predicted pose(e.g., by extrapolating the predicted pose based on movement of the HMD5 ms or 10 ms prior to determining the predicted pose). The updated posemay be determined based on updated pose information that is provided toa pose tracker at a higher frequency than the rendering frame rate. Inone example, the updated pose information may be generated using alow-latency inertial measurement unit (IMU) or combination of IMU andcamera-based pose tracking. The updated image may comprise an imagerotation, translation, resizing (e.g., stretching or shrinking),shifting, or tilting of at least a portion of the pre-rendered image inorder to correct for differences between the predicted pose and theupdated pose (e.g., to compensate for an incorrect pose prediction whengenerating the pre-rendered image). The updated image may be generatedvia a homographic transformation of the pre-rendered image. In somecases, the homographic transformation may comprise an affinetransformation. The updated image may be generated using a pixel offsetadjustment or a combination of homographic transformations and pixeloffset adjustments. In some cases, the homographic transformationsand/or pixel offset adjustments may be generated downstream from thecore rendering pipeline (e.g., using a controller or processorintegrated with the display). In one embodiment, the pixel offsetadjustments may be performed using a display that incorporates shiftregisters or other circuitry for allowing the shifting of pixel valueswithin a pixel array of the display (e.g., similar to the operation of acharge-coupled device).

In some embodiments, the updated images comprising late stage graphicaladjustments of forward predicted rendered images may be generated usingvarious image reprojection techniques of varying computationalcomplexity. The image reprojection techniques may include per pixelreprojection (e.g., where each pixel of a rendered image is reprojectedbased on an updated pose), multi-plane homography (e.g., where multiplerendered images associated with multiple planes within a 3D scene areused to generate the composite updated image), single plane homography(e.g., where a single rendered image associated with a single planewithin a 3D scene is used to generate the updated image), affinehomography, and pixel offset based adjustments. The 2D plane (or a setof one or more 2D planes) within a 3D scene may be determined based onwhich virtual objects the end user of an HMD has been focusing on withina particular period of time. In one example, eye tracking may be used todetermine the most frequently viewed virtual objects within theparticular period of time (e.g., within the previous 50 ms or 500 ms).In the case of a single plane, the single plane may be selected based ona depth of the most frequently viewed virtual object within theparticular period of time (i.e., the single plane may be set based onthe location of the most frequently viewed virtual object within theaugmented reality environment). In the case of multiple planes, virtualobjects within an augmented reality environment may be segmented into aplurality of groups based on proximity to the multiple planes; forexample, a first virtual object may be mapped to a near plane if thenear plane is the closest plane to the first virtual object and a secondvirtual object may be mapped to a far plane if the far plane is theclosest plane to the second virtual object. A first rendered image maythen be generated including the first virtual object based on the nearplane and a second rendered image may be generated including the secondvirtual object based on the far plane.

In some embodiments, different graphical adjustments may be performed ondifferent portions of a pre-rendered image in order to incorporatehigher frequency pose estimates. In one example, a first homographictransformation associated with a first pose of an HMD at a first pointin time may be applied to a first portion of the pre-rendered image(e.g., a top portion of the pre-rendered image) and a second homographictransformation associated with a second pose of the HMD at a secondpoint in time subsequent to the first point in time may be applied to asecond portion of the pre-rendered image different from the firstportion (e.g., a bottom portion of the pre-rendered image). In the caseof a scanning display or a progressive scanning display, the firsthomographic transformation may be applied to pixels associated with afirst set of scan lines and the second homographic transformation may beapplied to pixels associated with a second set of scan lines differentfrom the first set of scan lines. In one embodiment, the firsthomographic transformation may be applied to a single first scan lineand the second homographic transformation may be applied to a singlesecond scan line (i.e., homographic transformations may be applied on aper scan line basis).

One issue with generating a realistic augmented reality environmentrelates to the latency or amount of time in which images of world-lockedvirtual objects corresponding with a particular pose of an HMD aredisplayed to an end user of the HMD. For example, if too much timelapses between the time the end users head turns away from theparticular pose and the time an image of a virtual object is displayedbased on the particular pose, then the virtual object will appear todrift away from its intended location within the augmented realityenvironment (i.e., the image may not appear to be aligned with anintended real-world location or object). Thus, there is a need todisplay correctly aligned images of virtual objects to an end user inorder to improve virtual object stability and to improve the augmentedreality experience.

FIG. 1 is a block diagram of one embodiment of a networked computingenvironment 100 in which the disclosed technology may be practiced.Networked computing environment 100 includes a plurality of computingdevices interconnected through one or more networks 180. The one or morenetworks 180 allow a particular computing device to connect to andcommunicate with another computing device. The depicted computingdevices include mobile device 11, mobile device 12, mobile device 19,and server 15. In some embodiments, the plurality of computing devicesmay include other computing devices not shown. In some embodiments, theplurality of computing devices may include more than or less than thenumber of computing devices shown in FIG. 1. The one or more networks180 may include a secure network such as an enterprise private network,an unsecure network such as a wireless open network, a local areanetwork (LAN), a wide area network (WAN), and the Internet. Each networkof the one or more networks 180 may include hubs, bridges, routers,switches, and wired transmission media such as a wired network ordirect-wired connection.

Server 15, which may comprise a supplemental information server or anapplication server, may allow a client to download information (e.g.,text, audio, image, and video files) from the server or to perform asearch query related to particular information stored on the server. Ingeneral, a “server” may include a hardware device that acts as the hostin a client-server relationship or a software process that shares aresource with or performs work for one or more clients. Communicationbetween computing devices in a client-server relationship may beinitiated by a client sending a request to the server asking for accessto a particular resource or for particular work to be performed. Theserver may subsequently perform the actions requested and send aresponse back to the client.

One embodiment of server 15 includes a network interface 155, processor156, memory 157, and translator 158, all in communication with eachother. Network interface 155 allows server 15 to connect to one or morenetworks 180. Network interface 155 may include a wireless networkinterface, a modem, and/or a wired network interface. Processor 156allows server 15 to execute computer readable instructions stored inmemory 157 in order to perform processes discussed herein. Translator158 may include mapping logic for translating a first file of a firstfile format into a corresponding second file of a second file format(i.e., the second file may be a translated version of the first file).Translator 158 may be configured using file mapping instructions thatprovide instructions for mapping files of a first file format (orportions thereof) into corresponding files of a second file format.

One embodiment of mobile device 19 includes a network interface 145,processor 146, memory 147, camera 148, sensors 149, and display 150, allin communication with each other. Network interface 145 allows mobiledevice 19 to connect to one or more networks 180. Network interface 145may include a wireless network interface, a modem, and/or a wirednetwork interface. Processor 146 allows mobile device 19 to executecomputer readable instructions stored in memory 147 in order to performprocesses discussed herein. Camera 148 may capture color images and/ordepth images of an environment. The mobile device 19 may include outwardfacing cameras that capture images of the environment and inward facingcameras that capture images of the end user of the mobile device.Sensors 149 may generate motion and/or orientation informationassociated with mobile device 19. In some cases, sensors 149 maycomprise an inertial measurement unit (IMU). Display 150 may displaydigital images and/or videos. Display 150 may comprise a see-throughdisplay. Display 150 may comprise an LED or OLED display.

In some embodiments, various components of mobile device 19 includingthe network interface 145, processor 146, memory 147, camera 148, andsensors 149 may be integrated on a single chip substrate. In oneexample, the network interface 145, processor 146, memory 147, camera148, and sensors 149 may be integrated as a system on a chip (SOC). Inother embodiments, the network interface 145, processor 146, memory 147,camera 148, and sensors 149 may be integrated within a single package.

In some embodiments, mobile device 19 may provide a natural userinterface (NUI) by employing camera 148, sensors 149, and gesturerecognition software running on processor 146. With a natural userinterface, a person's body parts and movements may be detected,interpreted, and used to control various aspects of a computingapplication. In one example, a computing device utilizing a natural userinterface may infer the intent of a person interacting with thecomputing device (e.g., that the end user has performed a particulargesture in order to control the computing device).

Networked computing environment 100 may provide a cloud computingenvironment for one or more computing devices. Cloud computing refers toInternet-based computing, wherein shared resources, software, and/orinformation are provided to one or more computing devices on-demand viathe Internet (or other global network). The term “cloud” is used as ametaphor for the Internet, based on the cloud drawings used in computernetworking diagrams to depict the Internet as an abstraction of theunderlying infrastructure it represents.

In one example, mobile device 19 comprises a head-mounted display device(HMD) that provides an augmented reality environment or a mixed realityenvironment to an end user of the HMD. The HMD may comprise a videosee-through and/or an optical see-through system. An optical see-throughHMD worn by an end user may allow actual direct viewing of a real-worldenvironment (e.g., via transparent lenses) and may, at the same time,project images of a virtual object into the visual field of the end userthereby augmenting the real-world environment perceived by the end userwith the virtual object.

Utilizing an HMD, an end user may move around a real-world environment(e.g., a living room) wearing the HMD and perceive views of thereal-world overlaid with images of virtual objects. The virtual objectsmay appear to maintain coherent spatial relationship with the real-worldenvironment (i.e., as the end user turns their head or moves within thereal-world environment, the images displayed to the end user will changesuch that the virtual objects appear to exist within the real-worldenvironment as perceived by the end user). The virtual objects may alsoappear fixed with respect to the end user's point of view (e.g., avirtual menu that always appears in the top right corner of the enduser's point of view regardless of how the end user turns their head ormoves within the real-world environment). In one embodiment,environmental mapping of the real-world environment may be performed byserver 15 (i.e., on the server side) while camera localization may beperformed on mobile device 19 (i.e., on the client side). The virtualobjects may include a text description associated with a real-worldobject.

In some embodiments, a mobile device, such as mobile device 19, may bein communication with a server in the cloud, such as server 15, and mayprovide to the server location information (e.g., the location of themobile device via GPS coordinates) and/or image information (e.g.,information regarding objects detected within a field of view of themobile device) associated with the mobile device. In response, theserver may transmit to the mobile device one or more virtual objectsbased upon the location information and/or image information provided tothe server. In one embodiment, the mobile device 19 may specify aparticular file format for receiving the one or more virtual objects andserver 15 may transmit to the mobile device 19 the one or more virtualobjects embodied within a file of the particular file format.

In some embodiments, an HMD, such as mobile device 19, may use images ofan environment captured from an outward facing camera in order todetermine a six degree of freedom (6DOF) pose corresponding with theimages relative to a 3D map of the environment. The 6DOF pose maycomprise information associated with the position and orientation of theHMD within the environment. The 6DOF pose may be used for localizing theHMD and for generating images of virtual objects such that the virtualobjects appear to exist at appropriate locations within the environment.More information regarding determining a 6DOF pose can be found in U.S.patent application Ser. No. 13/152,220, “Distributed AsynchronousLocalization and Mapping for Augmented Reality,” incorporated herein byreference in its entirety. More information regarding performing poseestimation and/or localization for a mobile device can be found in U.S.patent application Ser. No. 13/017,474, “Mobile Camera LocalizationUsing Depth Maps,” incorporated herein by reference in its entirety.

In some embodiments, an HMD, such as mobile device 19, may displayimages of virtual objects within an augmented reality (AR) environmentat a frame rate that is greater than a rendering frame rate for the corerendering pipeline or rendering GPU. The HMD may modify pre-renderedimages or forward predicted images that are rendered at the renderingframe rate based on updated pose estimates that are provided at a higherfrequency than the rendering frame rate. In some embodiments, the HMDmay generate the pre-rendered image based on a predicted pose at therendering frame rate (e.g., every 16 ms), determine one or more updatedposes associated with the HMD subsequent to generating the pre-renderedimage (e.g., every 2 ms), generate one or more updated images based onthe one or more updated poses and the pre-rendered image, and displaythe one or more updated images on the HMD. In some cases, the one ormore updated images may be generated via homographic transformationsand/or a pixel offset adjustments using circuitry within the display,such as display 150.

FIG. 2A depicts one embodiment of a mobile device 19 in communicationwith a second mobile device 5. Mobile device 19 may comprise asee-through HMD. As depicted, mobile device 19 communicates with mobiledevice 5 via a wired connection 6. However, the mobile device 19 mayalso communicate with mobile device 5 via a wireless connection. Mobiledevice 5 may be used by mobile device 19 in order to offload computeintensive processing tasks (e.g., the rendering of virtual objects) andto store virtual object information and other data that may be used toprovide an augmented reality environment on mobile device 19. Mobiledevice 5 may also provide motion and/or orientation informationassociated with mobile device 5 to mobile device 19. In one example, themotion information may include a velocity or acceleration associatedwith the mobile device 5 and the orientation information may includeEuler angles, which provide rotational information around a particularcoordinate system or frame of reference. In some cases, mobile device 5may include a motion and orientation sensor, such as an inertialmeasurement unit (IMU), in order to acquire motion and/or orientationinformation associated with mobile device 5.

FIG. 2B depicts one embodiment of a portion of an HMD, such as mobiledevice 19 in FIG. 1. Only the right side of an HMD 200 is depicted. HMD200 includes right temple 202, nose bridge 204, eye glass 216, and eyeglass frame 214. Right temple 202 includes a capture device 213 (e.g., afront facing camera and/or microphone) in communication with processingunit 236. The capture device 213 may include one or more cameras forrecording digital images and/or videos and may transmit the visualrecordings to processing unit 236. The one or more cameras may capturecolor information, IR information, and/or depth information. The capturedevice 213 may also include one or more microphones for recording soundsand may transmit the audio recordings to processing unit 236.

Right temple 202 also includes biometric sensor 220, eye tracking system221, ear phones 230, motion and orientation sensor 238, GPS receiver232, power supply 239, and wireless interface 237, all in communicationwith processing unit 236. Biometric sensor 220 may include one or moreelectrodes for determining a pulse or heart rate associated with an enduser of HMD 200 and a temperature sensor for determining a bodytemperature associated with the end user of HMD 200. In one embodiment,biometric sensor 220 includes a pulse rate measuring sensor whichpresses against the temple of the end user. Motion and orientationsensor 238 may include a three axis magnetometer, a three axis gyro,and/or a three axis accelerometer. In one embodiment, the motion andorientation sensor 238 may comprise an inertial measurement unit (IMU).The GPS receiver may determine a GPS location associated with HMD 200.Processing unit 236 may include one or more processors and a memory forstoring computer readable instructions to be executed on the one or moreprocessors. The memory may also store other types of data to be executedon the one or more processors.

In one embodiment, the eye tracking system 221 may include one or moreinward facing cameras. In another embodiment, the eye tracking system221 may comprise an eye tracking illumination source and an associatedeye tracking image sensor. In one embodiment, the eye trackingillumination source may include one or more infrared (IR) emitters suchas an infrared light emitting diode (LED) or a laser (e.g. VCSEL)emitting about a predetermined IR wavelength or a range of wavelengths.In some embodiments, the eye tracking sensor may include an IR camera oran IR position sensitive detector (PSD) for tracking glint positions.More information about eye tracking systems can be found in U.S. Pat.No. 7,401,920, entitled “Head Mounted Eye Tracking and Display System”,issued Jul. 22, 2008, and U.S. patent application Ser. No. 13/245,700,entitled “Integrated Eye Tracking and Display System,” filed Sep. 26,2011, both of which are herein incorporated by reference.

In one embodiment, eye glass 216 may comprise a see-through display,whereby images generated by processing unit 236 may be projected and/ordisplayed on the see-through display. The see-through display maydisplay images of virtual objects by modulating light provided to thedisplay, such as a liquid crystal on silicon (LCOS) display, or bygenerating light within the display, such as an OLED display. Thecapture device 213 may be calibrated such that a field of view capturedby the capture device 213 corresponds with the field of view as seen byan end user of HMD 200. The ear phones 230 may be used to output soundsassociated with the projected images of virtual objects. In someembodiments, HMD 200 may include two or more front facing cameras (e.g.,one on each temple) in order to obtain depth from stereo informationassociated with the field of view captured by the front facing cameras.The two or more front facing cameras may also comprise 3D, IR, and/orRGB cameras. Depth information may also be acquired from a single camerautilizing depth from motion techniques. For example, two images may beacquired from the single camera associated with two different points inspace at different points in time. Parallax calculations may then beperformed given position information regarding the two different pointsin space.

In some embodiments, HMD 200 may perform gaze detection for each eye ofan end user's eyes using gaze detection elements and a three-dimensionalcoordinate system in relation to one or more human eye elements such asa cornea center, a center of eyeball rotation, or a pupil center. Gazedetection may be used to identify where the end user is focusing withina field of view. Examples of gaze detection elements may include glintgenerating illuminators and sensors for capturing data representing thegenerated glints. In some cases, the center of the cornea can bedetermined based on two glints using planar geometry. The center of thecornea links the pupil center and the center of rotation of the eyeball,which may be treated as a fixed location for determining an optical axisof the end user's eye at a certain gaze or viewing angle.

In one embodiment, the processing unit 236 may include a core renderingpipeline (e.g., comprising one or more graphical processing units) forgenerating pre-rendered images and a display associated with eye glass216 may perform late stage graphical adjustments to the pre-renderedimages based on later stage pose information associated with the HMD200. As updated pose information may be provided at a higher frequencythan a maximum rendering frame rate for the core rendering pipeline, thelate stage graphical adjustments may be applied to the pre-renderedimages at a frequency that is greater than the maximum rendering framerate.

FIG. 3A depicts one embodiment of a system for generating and displayingimages associated with a virtual object (or more than one virtualobject) at a frame rate that is greater than a rendering frame rate fora core rendering pipeline. As depicted, rendering module 302 maygenerate a pre-rendered image corresponding with a particular pose of anHMD. The particular pose may be provided to the rendering module 302 bypose estimation module 312. The pose estimation module 312 may predict afuture pose of the HMD based on movement history of the HMD. In someembodiments, the pose estimation module 312 may predict more than onefuture pose of the HMD (e.g., three possible future poses for the HMD)and the rendering module 302 may generate a plurality of pre-renderedimages corresponding with the more than one future poses. When updatedpose information becomes available, the closest pose (i.e., the bestpredicted pose) of the more than one future poses and the correspondingpre-rendered images for the closest pose may be used for generatingupdated images by applying late stage graphical adjustments to thecorresponding pre-rendered images for the closest pose. In oneembodiment, when updated pose information becomes available, instead ofa pre-rendered image associated with the closest pose of the more thanone future poses being selected, the updated images may be generatedusing images that are extrapolated and/or interpolated from theplurality of pre-rendered images corresponding with the more than onefuture poses.

In some cases, the pose estimation module 312 may determine a currentpose of the HMD based on camera-based pose tracking information and/or acombination of camera-based pose tracking information and low-latencyIMU motion information. The pose estimation module 312 may predict afuture pose of the HMD by extrapolating previous movement of the HMD(e.g., the movement of the HMD 5 ms or 10 ms prior to determining thecurrent pose).

A late stage reprojection (LSR) module 308 may perform late stagegraphical adjustments to pre-rendered images generated by the renderingmodule 302 based on updated pose estimation information provided by thepose estimation module 312. In one embodiment, the rendering module 302may generate pre-rendered images every 16 ms or every 32 ms and the LSRmodule 308 may generate adjusted images every 2 ms or every 4 ms (i.e.,the LSR module 308 may provide images to the display 310 at a frame ratethat is greater than the maximum rendering frame rate of the renderingmodule 302). As depicted, the LSR module 308 includes an imageadjustment module 304 and a pixel adjustment module 306. The imageadjustment module 304 may generate adjusted images by applyinghomographic transformations to the pre-rendered images (e.g., applying asingle plane homography or a multi-plane homography). In one example,the image adjustment module 304 may apply an affine transformation to apre-rendered image. The pixel adjustment module 306 may perform atwo-dimensional pixel shifting of an image. The image that is pixelshifted by the pixel adjustment module 306 may comprise a portion of apre-rendered image or a portion of an image generated by the imageadjustment module 304. In some cases, the LSR module 308 may generate anadjusted image by applying a homographic transformation to apre-rendered image and then applying a pixel offset adjustment to theimage generated via the homographic transformation. The adjusted imagesgenerated by the LSR module 308 may be displayed on display 310. In oneembodiment, the display 310 may comprise an OLED display.

In some embodiments, portions of the LSR module 308 may be integratedwith the display 310. In one example, the pixel adjustment module 306may be performed using shift registers or other circuitry within thedisplay 310 for allowing the shifting of pixel values within a pixelarray of the display 310. In another example, both the image adjustmentmodule 304 and the pixel adjustment module 306 may be performed by acontroller or processor integrated with the display 310.

FIG. 3B depicts one embodiment of display 310 in FIG. 3A. As depicted,the display includes a pixel array 320 driven by row drivers 322 anddata line drivers 224. The pixel array 320 comprises a plurality ofpixels 321. In one embodiment, each pixel 321 may comprise an OLEDpixel. Each OLED pixel may comprise an OLED and a group of circuits forcontrolling the OLED. The row drivers 322 may drive row lines (or scanlines) for selecting a particular row of pixels within the pixel array320 and for connecting data lines corresponding with the data linedrivers 324 to pixels in the particular row of pixels. Each row lineassociated with the row drivers 322 may connect to latching TFTs withineach pixel of the particular row of pixels. A latching TFT may isolate astorage capacitor from a particular data line of the data lines (e.g., aparticular column data line connected to each pixel in a column of thepixel array). The storage capacitor may be used to store a voltage forbiasing a gate of a second TFT that drives an OLED. The controller 326may load pixel values into the pixel array 320 by controlling the rowdrivers 322 and the data line drivers 324. The controller 326 may accessbuffered images stored in buffer 328 and perform image adjustments priorto loading pixel values into the pixel array 320.

In one embodiment, controller 326 may perform a particular homographictransformation to an image (or a portion of an image) stored in buffer328 and then load the adjusted image into the pixel array 320 fordisplay. The controller 326 may also perform a pixel offset adjustmentto an image stored in buffer 328 (e.g., by shifting the pixel values ofthe image by a first pixel offset in the X-direction and a second pixeloffset in the Y-direction).

FIG. 3C depicts an alternative embodiment of display 310 in FIG. 3A. Asdepicted, the display includes a pixel array 330 driven by row drivers322 and data line drivers 224. The pixel array 330 comprises a pluralityof pixels 331. In one embodiment, each pixel 331 may comprise an OLEDpixel. Each OLED pixel may comprise an OLED, a first group of circuitsfor controlling the OLED, and a second group of circuits for performingpixel shifting within the pixel array 330. The pixel array 330 mayinclude pixel interconnections 333 between adjacent pixels forfacilitating the shifting of pixel values within the pixel array. In oneembodiment, latched data values may be shifted vertically (i.e., in thecolumn direction) and/or horizontally (i.e., in the row direction)between adjacent pixels. In another embodiment, data values stored on astorage capacitor for a particular pixel may be used to drive one of aplurality OLEDs within the pixel array 330 (i.e., rather than physicallyshifting the latched data value, a multiplexor within each pixel may beused to select the correct latched data value to apply to itscorresponding OLED).

The row drivers 322 may drive row lines (or scan lines) for selecting aparticular row of pixels within the pixel array 330 and for connectingdata lines corresponding with the data line drivers 324 to pixels in theparticular row of pixels. Each row line associated with the row drivers322 may connect to latching TFTs within each pixel of the particular rowof pixels. A latching TFT may isolate a storage capacitor from aparticular data line of the data lines (e.g., a particular column dataline connected to pixels in a column of the pixel array). The storagecapacitor may be used to store a voltage for biasing a second TFT thatdrives an OLED (e.g., for controlling the gate of the second TFT). Inone embodiment, each pixel 331 may include a multiplexor for selectingone of a plurality of latched data values (each stored on a storagecapacitor within the pixel array) for driving a TFT that drives the OLEDfor the pixel. In some cases, the multiplexor may allow for the shiftingof displayed pixel values within the pixel array 330 by a first pixeloffset in the X-direction and a second pixel offset in the Y-direction.The controller 332 may load pixel values into the pixel array 330 bycontrolling the row drivers 322 and the data line drivers 324. Thecontroller 332 may perform image adjustments prior to loading pixelvalues into the pixel array 330. The controller 332 may include a memorybuffer for buffering image information provided to the display 310.

In one embodiment, controller 332 may perform a particular homographictransformation to an image then load pixel values associated with theimage into the pixel array 330. The controller may subsequently performa pixel offset adjustment by shifting the pixel values within the pixelarray 331. In one example, latched data values within each pixel may bephysically shifted vertically (i.e., in the column direction) and/orhorizontally (i.e., in the row direction) within the pixel array viapixel interconnections 333. In another example, latched data values maybe used to drive one of a plurality OLEDs within the pixel array 330 byincorporating a multiplexor within each pixel 331 of the pixel array330. In some cases, the pixel array 330 may utilize a CMOS backplane. Inother cases, the pixel array 330 may utilize a CCD backplane.

FIG. 4A depicts one embodiment of a portion of a pre-rendered image 412and an updated image 414 based on the pre-rendered image 412. Asdepicted, the pre-rendered image 412 may be rendered based on an initialpose estimate for an HMD (e.g., a predicted pose of the HMD 8 ms or 16ms into the future). The initial pose estimate may be determined basedon a current position and orientation of the HMD and an acceleration anda velocity of the HMD immediately prior to determining the initial poseestimate. The pre-rendered image 412 may comprise a rendered image basedon the initial pose estimate and may be rendered using a GPU or otherrendering system that has the ability to render a three-dimensionalscene into a two-dimensional image given a particular pose. The updatedpose estimate may be determined based on updated pose information thatis acquired at a point in time subsequent to the determination of theinitial pose estimate. In one example, the updated pose information maybe generated based on camera-based pose tracking information and/or acombination of camera-based pose tracking information and low-latencyIMU motion information corresponding with the HMD.

In some embodiments, the updated image 414 may be generated by applyingan image transformation to the pre-rendered image 412 based on a posedifference between the updated pose estimate and the initial poseestimate. In one example, the image transformation may comprise an imagerotation, translation, resizing (e.g., stretching or shrinking),shifting, or tilting of at least a portion of the pre-rendered image412. The updated image 414 may be generated via a homographictransformation of the pre-rendered image 412. In some cases, thehomographic transformation may comprise a multi-plane homography, asingle plane homography, and/or an affine homography.

In some embodiments, the updated image 414 may be generated by applyinga pixel offset adjustment to the pre-rendered image 402. The degree ofthe pixel offset adjustment may depend on a difference between theupdated pose estimate and the initial pose estimate. As depicted, animage 413 of a virtual object (i.e., a virtual cylinder) has been pixelshifted in both the X-dimension and the Y-dimension (e.g., by 4 pixelsto the left and by 3 pixels up). In one embodiment, the updated image414 may be generated using a pixel offset adjustment or a combination ofhomographic transformations and pixel offset adjustments. Thehomographic transformations and/or pixel offset adjustments may begenerated using a controller or processor integrated with a display. Insome cases, the pixel offset adjustments may be performed using adisplay that incorporates shift registers or other circuitry forallowing the shifting of pixel values within a pixel array of thedisplay.

FIG. 4B depicts one embodiment of a pre-rendered image 422 and samplingregions 424 and 426 used for generating updated images (or targetimages) based on portions of the pre-rendered image 422. As depicted,pre-rendered image 422 includes an image of a virtual object 421 (i.e.,a virtual cylinder). In one embodiment, the sampling region 424 maycorrespond with a first homographic transformation for generating afirst updated image and the sampling region 426 may correspond with asecond homographic transformation for generating a second updated image.A homographic transformation may comprise a weighted mapping betweenpixels (or points) within the pre-rendered image (i.e., the source imageor source frame) and points within an updated image (i.e., the targetimage or target frame). The four corners of a sampling region maycorrespond with the four corners of a corresponding updated image. Inone embodiment, the quadrilateral region associated with sampling region424 (i.e., a first subset of points within the source image) may bemapped to a second quadrilateral region associated with an updated image(i.e., a second subset of points within the target image). In somecases, the sampling region 424 may derive from a portion of an imagewithin a frame buffer of a core rendering pipeline or rendering GPU. Inthe case of affine homography, points within a first parallelogramregion within a source image may be mapped to points within a secondparallelogram region within a target image (or to the entire targetimage comprising a rectangular region).

As depicted, a source image may be larger than a corresponding targetimage. The source image may be over-rendered to account for potentialhead movements beyond a current point of view or pose. In one example,the source image may comprise an image that is 1920 pixels by 1080pixels and the target image may comprise an image that is 1366 pixels by768 pixels. Assuming a one to one mapping, the sampling regions 424 and426 may both comprise images that are 1366 pixels by 768 pixels. In someembodiments, each pixel within the target image may correspond with aweighted mapping of four or more pixels within the source image. Themapping of source pixels from a sampling region of the source image intotarget pixels of a target image may include bilinear filtering (or othertexture filtering) of the source pixels. In some cases, a distortioncorrection mapping may be applied to the source image prior to applyinga homographic transformation.

In one embodiment, the sampling region 424 (and first homographictransformation) may be associated with a first pose (or a firstpredicted pose) of an HMD at a first point in time and the samplingregion 426 (and second homographic transformation) may be associatedwith a second pose (or a second predicted pose) of the HMD at a secondpoint in time subsequent to the first point in time (e.g., 2 ms or 4 msafter the first point in time). In one example, the first predicted posemay correspond with a predicted pose that is 4 ms into the future andthe second predicted pose may correspond with a predicted pose that is 8ms into the future. A first updated image corresponding with the firsthomographic transformation may be displayed prior to a second updatedimage corresponding with the second homographic transformation beingdisplay. The first updated image may be displayed while the secondupdated image is being generated.

In one embodiment, the sampling region 424 in FIG. 4B may correspondwith a first homographic transformation for generating a first portionof a target image (e.g., a top portion of the target image) and thesampling region 426 in FIG. 4B may correspond with a second homographictransformation for generating a second portion of the target image(e.g., a bottom portion of the target image).

FIG. 4C depicts one embodiment of the pre-rendered image 422 of FIG. 4Bwherein a rolling buffer 432 (e.g., spanning a particular number of rowsor scan lines) is applied to the pre-rendered image 422. In some cases,the pre-rendered image 422 may comprise a plurality of segments (e.g.,each spanning 10 rows) and the rolling buffer 432 may correspond withone of the plurality of segments at a particular point in time (e.g.,the rolling buffer 432 may move between each of the plurality ofsegments in a top to bottom sequence). The rolling buffer 432 maydetermine the source pixels within the pre-rendered image 422 that maybe operated on at a particular point in time. In some cases, ahomographic transformation may apply to a subset of the source pixelswithin the rolling buffer 432 (e.g., corresponding with the overlap ofthe sampling region 424 of FIG. 4B and the source image rows pointed toby the rolling buffer 432).

The concept of applying a rolling buffer to a source image may also beapplied to the target image. In some embodiments, a homographictransformation may correspond with a subset of target pixels within thetarget image. For example, a rolling buffer may be applied to the targetimage such that a homography (or other image transformation) is appliedto the subset of target pixels. The subset of target pixels maycorrespond with a set of scan lines within the target image (e.g., thesubset of target pixels comprises pixels spanning 20 rows of the targetimage). In this case of a scanning display, image reprojectiontechniques may be applied to pixels that will be updated within aparticular time period (e.g., a homographic transformation need onlyapply to those pixels within the target image that will be displayed orupdated within the next 2 ms).

FIG. 5A depicts one embodiment of applying late stage graphicaladjustments to a rendered image in order to generate updated images. Theupdated image may be displayed using an HMD. As depicted, a renderedimage (Image X) is available by time T2. The overall time for renderingthe rendered image may be, for example, 16 ms, 30 ms, or 60 ms dependingon the core rendering pipeline for generated the rendered image. Priorto the rendered image becoming available at time T2, a pose estimate(P1) may be initiated at time T1 and used to generate an updated image(Image A) by time T2 based on the rendered image. The updated image(Image A) may be displayed between times T2 and T6 using a display ofthe HMD. In one embodiment, the pose estimate (P1) may correspond with apredicted pose of an HMD at time T4 (or another point in time duringwhich an image is projected using the HMD). In some embodiments, thetime for the predicted pose may correspond with a middle display timefor the display of the updated image (Image A) derived from the renderedimage (Image X). The middle display time for the display of the updatedimage may correspond with the center photon of the projection or themidpoint of the projection time. At time T5, a second pose estimate (P2)may be initiated and used to generate a second updated image (Image B)by time T6. The second updated image (Image B) may be displayedbeginning at time T6.

In one example, a display may display updated images every 4 ms (i.e.,the time between T2 and T6 may be 4 ms). Prior to the rendered image(Image X) becoming available, a predicted pose corresponding with amiddle display time for an updated image may be determined. As thepredicted pose is initiated at time T1 and the updated image will bedisplayed for 4 ms, the predicted pose may correspond with a predictedpose 3 ms into the future from time T1. One reason for forwardpredicting to the middle display time is that error due to displaylatency may be minimized or centered around the middle display time.

In one embodiment, a display may comprise a field-sequential colordisplay and the updated image (Image A) may correspond with a firstcolor field (e.g., a red image) and the second updated image (Image B)may correspond with a second color field (e.g., a green image). In thiscase, the pose estimate (P1) may be used for generating the updatedimage (Image A) associated with the first color field and the secondpose estimate (P2) may be used for generating the second updated image(Image B) associated with the second color field. In some cases, theupdated image (Image A) may be generated using a pixel offset adjustmentof the rendered image (Image X) and the second updated image (Image B)may be generated using a homographic transformation of the renderedimage (Image X) and/or a second pixel offset adjustment of the renderedimage (Image X). The field-sequential color display may comprise, forexample, an OLED display or an LCOS display.

In one embodiment, a display may comprise a LCOS display that is drivenin a unipolar fashion, wherein a driving voltage may be reversed duringimage projection to prevent liquid crystal degradation. As each colorfield projection may correspond with both a positive projection (e.g.,the first 2 ms of an image projection) and a negative projection (e.g.,the last 2 ms of the image projection), a first updated image may beprojected during the positive projection and a second updated image maybe projected during the negative projection, thereby effectivelydoubling the display frame rate. In some cases, the first updated imagemay be generated via a first pixel offset adjustment by circuitryintegrated with the LCOS display and the second updated image may begenerated via a second pixel offset adjustment by circuitry integratedwith the LCOS display.

FIG. 5B depicts one embodiment of a display sequence associated with adisplay. The display sequence may correspond with a field-sequentialcolor display or a non-field-sequential color display. In oneembodiment, images associated with each color field of the red, green,and blue color fields may be loaded into the display at different pointsin time. For example, a first image (Load R) associated with the redcolor field may be loaded into the display between times T0 and T1, asecond image (Load G) associated with the green color field may beloaded into the display between times T1 and T2, and a third image (LoadB) associated with the blue color field may be loaded into the displaybetween times T2 and T3. As the second image (Load G) is being loadedinto the display, a red-homographic image (R-H) corresponding with ahomographic transformation of the first image and a blue-pixel-adjustedimage (B-P2) corresponding with a second pixel offset adjustment of apreviously loaded blue image may be displayed on the display. As thethird image (Load B) is being loaded into the display, agreen-homographic image (G-H) corresponding with a homographictransformation of the second image and a red-pixel-adjusted image (R-P1)corresponding with a first pixel offset adjustment of thered-homographic image (R-H) may be displayed on the display. Betweentimes T3 and T4, a blue-homographic image (B-H) corresponding with ahomographic transformation of the third image may be displayed while ared-pixel-adjusted image (R-P2) corresponding with a second pixel offsetadjustment of the red-homographic image (R-H) and a green-pixel-adjustedimage (G-P1) corresponding with a first pixel offset adjustment of thegreen-homographic image (G-H) are displayed. Between times T4 and T5, asthe next red color field image is being loaded into the display, agreen-pixel-adjusted image (G-P2) corresponding with a second pixeloffset adjustment of the green-homographic image (G-H) and ablue-pixel-adjusted image (B-P1) corresponding with a first pixel offsetadjustment of the blue-homographic image (B-H) are displayed. In somecases, the display may comprise an OLED display and the time betweentimes T1 and T5 may comprise roughly 8 ms.

In one embodiment, the homographic transformations to the loaded colorimages and any pixel offset adjustments to displayed images may beperformed by circuitry within the display. In another embodiment, thehomographic transformations to the color images and any pixel offsetadjustments to displayed images may be performed by a host device andtransmitted to the display.

FIG. 5C depicts an alternative embodiment of a display sequenceassociated with a display. The display sequence may correspond with afield-sequential color display or a non-field-sequential color display.In one embodiment, images associated with each color field of the red,green, and blue color fields may be loaded into the display at differentpoints in time. For example, a first image (R-L) associated with the redcolor field may be loaded into the display between times T0 and T1, asecond image (G-L) associated with the green color field may be loadedinto the display between times T1 and T2, and a third image (B-L)associated with the blue color field may be loaded into the displaybetween times T2 and T3. As the second image (G-L) is being loaded intothe display, a red-homographic image (R-H) corresponding with ahomographic transformation of the first image, a blue-pixel-adjustedimage (B-P2) corresponding with a second pixel offset adjustment of apreviously loaded blue image, and a green-pixel-adjusted image (G-P3)corresponding with a third pixel offset adjustment of a previouslyloaded green image may be displayed on the display (i.e., the G-P3 imagemay be displayed while the G-L image is loaded into the display). As thethird image (B-L) is being loaded into the display, a green-homographicimage (G-H) corresponding with a homographic transformation of thesecond image, a red-pixel-adjusted image (R-P1) corresponding with afirst pixel offset adjustment of the red-homographic image (R-H), and ablue-pixel-adjusted image (B-P3) corresponding with a third pixel offsetadjustment of a previously loaded blue image may be displayed on thedisplay (i.e., the B-P3 image may be displayed while the B-L image isloaded into the display). Between times T3 and T4, a blue-homographicimage (B-H) corresponding with a homographic transformation of the thirdimage may be displayed while a red-pixel-adjusted image (R-P2)corresponding with a second pixel offset adjustment of thered-homographic image (R-H) and a green-pixel-adjusted image (G-P1)corresponding with a first pixel offset adjustment of thegreen-homographic image (G-H) are displayed. Between times T4 and T5, asthe next red color field image is being loaded into the display, agreen-pixel-adjusted image (G-P2) corresponding with a second pixeloffset adjustment of the green-homographic image (G-H), ablue-pixel-adjusted image (B-P1) corresponding with a first pixel offsetadjustment of the blue-homographic image (B-H), and a red-pixel-adjustedimage (R-P3) corresponding with a third pixel offset adjustment of apreviously loaded red image may be displayed on the display (i.e., theR-P3 image may be displayed while the next red image is loaded into thedisplay). In some cases, the display may comprise an OLED display withan image buffer for allowing new images to be loaded while displayingother images and the time between times T1 and T5 may comprise roughly 8ms.

In one embodiment, the homographic transformations to the loaded colorimages and any pixel offset adjustments to displayed images may beperformed by circuitry within the display. In another embodiment, thehomographic transformations to the color images and any pixel offsetadjustments to displayed images may be performed by a host device andtransmitted to the display.

FIG. 6A is a flowchart describing one embodiment of a method forgenerating and displaying images associated with virtual objects at aframe rate that is greater than a rendering frame rate. In oneembodiment, the process of FIG. 6A may be performed by an HMD, such asmobile device 19 in FIG. 1.

In step 602, a pose history associated with an HMD is acquired. The posehistory may comprise positions, orientations, and movements of the HMDovertime. In step 604, a current pose of the HMD is determined. Thecurrent pose may be determined using camera-based pose tracking. In step606, a predicted pose of the HMD is determined based on the current poseand the pose history. The predicted pose may correspond with a firstpoint in time (e.g., 8 ms or 16 ms in the future from when the currentpose was determined).

In step 608, a rendered image is generated based on the predicted pose.The rendered image may be rendered using a GPU or other rendering systemthat has the ability to render a three-dimensional scene into atwo-dimensional image given the predicted pose. In step 610, an updatedpose of the HMD is determined corresponding with the first point intime. The updated pose may be determined using camera-based posetracking information and/or a combination of camera-based pose trackinginformation and low-latency IMU motion information.

In step 612, a pose difference between the predicted pose and theupdated pose is determined. The pose difference may determine a degreeof graphical adjustment to be applied to a portion of the rendered imagein order to compensate for an incorrect pose prediction when generatingthe rendered image.

In step 614, an updated image is generated based on the pose difference.The updated image may be generated via a homographic transformation of aportion of the rendered image. In some cases, the homographictransformation may comprise an affine transformation. The updated imagemay also be generated using a pixel offset adjustment or a combinationof homographic transformations and pixel offset adjustments. In somecases, the homographic transformations and/or pixel offset adjustmentsmay be generated using a controller or processor integrated with adisplay of the HMD. In one embodiment, the pixel offset adjustments maybe performed using a display of the HMD that incorporates shiftregisters or other circuitry for allowing the shifting of pixel valueswithin a pixel array of the display. In step 616, the updated image isdisplayed on the HMD. The updated image may be displayed using an OLEDdisplay integrated with the HMD.

FIG. 6B is a flowchart describing one embodiment of a method for makinggraphical adjustments to rendered images provided to a display usingcircuitry integrated with the display. In one embodiment, the process ofFIG. 6B may be performed by a display, such as display 150 in FIG. 1.

In step 632, an image is acquired from a host. The host may comprise acore rendering pipeline for generating images of virtual objects. Instep 634, a first updated image is generated by applying a homographictransformation to the image. The homographic transformation may comprisean affine transformation. In step 636, the first updated image is loadedinto a pixel array of a display. The display may comprise an OLEDdisplay. In step 638, the first updated image may be displayed using thedisplay.

In step 640, a second updated image may be generated by shifting thefirst updated image within the pixel array. In one embodiment, latcheddata values within the pixel array may be shifted vertically (i.e., inthe column direction) and/or horizontally (i.e., in the row direction)between adjacent pixels. In another embodiment, data values storedwithin the pixel array may drive one of a plurality LEDs within thepixel array (i.e., rather than physically shifting the latched datavalue, a multiplexor within each pixel may be used to select the correctlatched data value to apply to its corresponding LED). In step 642, thesecond updated image is displayed on the display.

FIG. 7A is a flowchart describing an alternative embodiment of a methodfor generating and displaying images associated with virtual objects ata frame rate that is greater than a rendering frame rate. In oneembodiment, the process of FIG. 7A may be performed by an HMD, such asmobile device 19 in FIG. 1.

In step 702, a first predicted pose associated with an HMD isdetermined. The first predicted pose of the HMD may be determined basedon a pose history of the HMD and may correspond with a future point intime during which an image based on the first predicted pose may bedisplayed or projected using a display of the HMD. In step 704, arendered image is generated based on the first predicted pose. Therendered image may be rendered using a GPU or other rendering systemthat has the ability to render a three-dimensional scene into atwo-dimensional image given the first predicted pose. In some cases, therendering system may take 30 ms or 60 ms to render the rendered image.Each rendered image generated by the rendering system may be associatedwith metadata identifying a particular pose from which the renderedimage was generated. One embodiment of a process for generating arendered image is described later in reference to FIG. 7B.

In step 706, a second predicted pose of the HMD is determined. Thesecond predicted pose may comprise an updated pose (e.g., an updatedpose estimate based on updated position and motion information of theHMD not available prior to determining the first predicted pose). Insome cases, the second predicted pose may be determined by extrapolatingcamera-based pose tracking information and/or a combination ofcamera-based pose tracking information and low-latency IMU motioninformation.

In some embodiments, the second predicted pose may correspond with amiddle display time for the display of an updated image derived from therendered image. The middle display time of an updated image maycorrespond with the center photon of the projection of the updated imageor the midpoint of the projection time of the updated image.

In step 708, a pose difference between the first predicted pose and thesecond predicted pose is determined. The pose difference may determine adegree of graphical adjustment to be applied to a portion of therendered image in order to compensate for an incorrect pose predictionwhen generating the rendered image. In some embodiments, if the posedifference is below a difference threshold, then a subsequent graphicaladjustment may comprise a pixel offset adjustment. If the posedifference is greater than or equal to the difference threshold, thenthe subsequent graphical adjustment may comprise a homography.

In step 710, an updated image is generated based on the pose differenceand at least a portion of the rendered image. The updated image may begenerated via a homographic transformation of a portion of the renderedimage. In some cases, the homographic transformation may comprise amulti-plane homography, a single plane homography, and/or an affinehomography. The updated image may also be generated using a pixel offsetadjustment or a combination of homographic transformations and pixeloffset adjustments. In some cases, the homographic transformationsand/or pixel offset adjustments may be generated using a controller orprocessor integrated with a display of the HMD or using custom circuitryintegrated within the display. In one embodiment, the pixel offsetadjustments may be performed using a display of the HMD thatincorporates shift registers or other circuitry for allowing theshifting of pixel values within a pixel array of the display. In step712, the updated image is displayed on the HMD. The updated image may bedisplayed using an OLED display or an LCOS display integrated with theHMD.

FIG. 7B is a flowchart describing one embodiment of a process forgenerating a rendered image. The process described in FIG. 7B is oneexample of a process for implementing step 704 in FIG. 7A. In oneembodiment, the process of FIG. 7B may be performed by an HMD, such asmobile device 19 in FIG. 1.

In step 722, a predicted pose of an HMD is acquired. The predicted posemay be acquired by querying a pose estimation module, such as poseestimation module 312 in FIG. 3A. In step 724, a virtual object beingfocused on by an end user of the HMD is identified. In one embodiment,eye tracking may be used to determine a set of viewed virtual objectsfocused on by the end user within a particular period of time. Thevirtual object may be identified as the most frequently viewed virtualobject of the sets of viewed virtual objects. The virtual object may beassociated with a depth or distance from the HMD.

In step 726, a stabilization plane is determined based on a location ofthe virtual object within an augmented reality environment. Thestabilization plane may coincide with the location of the virtual objectwithin the augmented reality environment. In this case, stabilizationplanes (and corresponding rendered images) may be determined on-the-flyas the end user shifts their focus among virtual objects within theaugmented reality environment over time (i.e., the location of thestabilization plane within the augmented reality environment may shiftbased on the location of the most frequently viewed virtual objectwithin the augmented reality environment during a particular period oftime). In step 728, a rendered image is generated based on the predictedpose and the stabilization plane. The rendered image may comprise atwo-dimensional image within the stabilization plane. In step 730, therendered image is outputted.

One embodiment of the disclosed technology includes one or moreprocessors in communication with a see-through display. The one or moreprocessors generate a rendered image associated with a first predictedpose of the mobile device and determine a second predicted pose of themobile device. The second predicted pose is different from the firstpredicted pose. The second predicted pose corresponds with a point intime during which an updated image is displayed. The one or moreprocessors determine a pose difference between the first predicted poseand the second predicted pose and generate the updated image based onthe pose difference and at least a portion of the rendered image. Thesee-through display displays the updated image.

One embodiment of the disclosed technology includes generating arendered image associated with a first predicted pose of a mobile deviceand determining a second predicted pose of the mobile device. The secondpredicted pose is different from the first predicted pose andcorresponds with a point in time during which an updated image isdisplayed on the mobile device. The method further comprises determininga pose difference between the first predicted pose and the secondpredicted pose, generating at least a portion of an updated image basedon the pose difference and at least a portion of the rendered image, anddisplaying the at least a portion of the updated image on a display ofthe mobile device.

One embodiment of the disclosed technology includes determining a firstpredicted pose associated with the HMD, generating a rendered imagebased on the first predicted pose, and determining a second predictedpose associated with the HMD subsequent to the determining a firstpredicted pose. The second predicted pose corresponds with a middledisplay time for displaying an updated image on the HMD (e.g., a timecorresponding with a center photon for the projected image). The methodfurther comprises determining a pose difference between the firstpredicted pose and the second predicted pose, generating the updatedimage based on the pose difference and at least a portion of therendered image, and displaying the updated image using the HMD.

FIG. 8 is a block diagram of one embodiment of a mobile device 8300,such as mobile device 19 in FIG. 1. Mobile devices may include laptopcomputers, pocket computers, mobile phones, HMDs, personal digitalassistants, and handheld media devices that have been integrated withwireless receiver/transmitter technology.

Mobile device 8300 includes one or more processors 8312 and memory 8310.Memory 8310 includes applications 8330 and non-volatile storage 8340.Memory 8310 can be any variety of memory storage media types, includingnon-volatile and volatile memory. A mobile device operating systemhandles the different operations of the mobile device 8300 and maycontain user interfaces for operations, such as placing and receivingphone calls, text messaging, checking voicemail, and the like. Theapplications 8330 can be any assortment of programs, such as a cameraapplication for photos and/or videos, an address book, a calendarapplication, a media player, an internet browser, games, an alarmapplication, and other applications. The non-volatile storage component8340 in memory 8310 may contain data such as music, photos, contactdata, scheduling data, and other files.

The one or more processors 8312 are in communication with a see-throughdisplay 8309. The see-through display 8309 may display one or morevirtual objects associated with a real-world environment. The one ormore processors 8312 also communicates with RF transmitter/receiver 8306which in turn is coupled to an antenna 8302, with infraredtransmitter/receiver 8308, with global positioning service (GPS)receiver 8365, and with movement/orientation sensor 8314 which mayinclude an accelerometer and/or magnetometer. RF transmitter/receiver8308 may enable wireless communication via various wireless technologystandards such as Bluetooth® or the IEEE 802.11 standards.Accelerometers have been incorporated into mobile devices to enableapplications such as intelligent user interface applications that letusers input commands through gestures, and orientation applicationswhich can automatically change the display from portrait to landscapewhen the mobile device is rotated. An accelerometer can be provided,e.g., by a micro-electromechanical system (MEMS) which is a tinymechanical device (of micrometer dimensions) built onto a semiconductorchip. Acceleration direction, as well as orientation, vibration, andshock can be sensed. The one or more processors 8312 further communicatewith a ringer/vibrator 8316, a user interface keypad/screen 8318, aspeaker 8320, a microphone 8322, a camera 8324, a light sensor 8326, anda temperature sensor 8328. The user interface keypad/screen may includea touch-sensitive screen display.

The one or more processors 8312 controls transmission and reception ofwireless signals. During a transmission mode, the one or more processors8312 provide voice signals from microphone 8322, or other data signals,to the RF transmitter/receiver 8306. The transmitter/receiver 8306transmits the signals through the antenna 8302. The ringer/vibrator 8316is used to signal an incoming call, text message, calendar reminder,alarm clock reminder, or other notification to the user. During areceiving mode, the RF transmitter/receiver 8306 receives a voice signalor data signal from a remote station through the antenna 8302. Areceived voice signal is provided to the speaker 8320 while otherreceived data signals are processed appropriately.

Additionally, a physical connector 8388 may be used to connect themobile device 8300 to an external power source, such as an AC adapter orpowered docking station, in order to recharge battery 8304. The physicalconnector 8388 may also be used as a data connection to an externalcomputing device. The data connection allows for operations such assynchronizing mobile device data with the computing data on anotherdevice.

The disclosed technology is operational with numerous other generalpurpose or special purpose computing system environments orconfigurations. Examples of well-known computing systems, environments,and/or configurations that may be suitable for use with the technologyinclude, but are not limited to, personal computers, server computers,hand-held or laptop devices, multiprocessor systems,microprocessor-based systems, set top boxes, programmable consumerelectronics, network PCs, minicomputers, mainframe computers,distributed computing environments that include any of the above systemsor devices, and the like.

The disclosed technology may be described in the general context ofcomputer-executable instructions, such as program modules, beingexecuted by a computer. Generally, software and program modules asdescribed herein include routines, programs, objects, components, datastructures, and other types of structures that perform particular tasksor implement particular abstract data types. Hardware or combinations ofhardware and software may be substituted for software modules asdescribed herein.

The disclosed technology may also be practiced in distributed computingenvironments where tasks are performed by remote processing devices thatare linked through a communications network. In a distributed computingenvironment, program modules may be located in both local and remotecomputer storage media including memory storage devices.

For purposes of this document, each process associated with thedisclosed technology may be performed continuously and by one or morecomputing devices. Each step in a process may be performed by the sameor different computing devices as those used in other steps, and eachstep need not necessarily be performed by a single computing device.

For purposes of this document, reference in the specification to “anembodiment,” “one embodiment,” “some embodiments,” or “anotherembodiment” may be used to described different embodiments and do notnecessarily refer to the same embodiment.

For purposes of this document, a connection can be a direct connectionor an indirect connection (e.g., via another part).

For purposes of this document, the term “set” of objects, refers to a“set” of one or more of the objects.

Although the subject matter has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described above.Rather, the specific features and acts described above are disclosed asexample forms of implementing the claims.

What is claimed is:
 1. A mobile device, comprising: one or moreprocessors, the one or more processors generate a rendered imageassociated with a first predicted pose of the mobile device, the one ormore processors determine a second predicted pose of the mobile device,the second predicted pose is different from the first predicted pose,the second predicted pose corresponds with a point in time during whichan updated image is displayed, the one or more processors determine apose difference between the first predicted pose and the secondpredicted pose, the one or more processors generate the updated imagebased on the pose difference and at least a portion of the renderedimage; and a see-through display in communication with the one or moreprocessors, the see-through display displays the updated image.
 2. Themobile device of claim 1, wherein: the second predicted pose correspondswith a middle display time for displaying the updated image on themobile device.
 3. The mobile device of claim 1, wherein: the one or moreprocessors identify a virtual object being focused on by an end user ofthe mobile device, the one or more processors determine a stabilizationplane based on a location of the virtual object within an augmentedreality environment, the one or more processors generate the renderedimage based on the stabilization plane.
 4. The mobile device of claim 1,wherein: the one or more processors generate the updated image byapplying a homographic transformation to the at least a portion of therendered image.
 5. The mobile device of claim 4, wherein: thehomographic transformation comprises a multi-plane homography.
 6. Themobile device of claim 4, wherein: the homographic transformationcomprises an affine homography.
 7. The mobile device of claim 1,wherein: the mobile device comprises an HMD.
 8. A method for displayingimages using a mobile device, comprising: generating a rendered image,the rendered image is associated with a first predicted pose of themobile device; determining a second predicted pose of the mobile device,the second predicted pose is different from the first predicted pose andcorresponds with a point in time during which an updated image isdisplayed on the mobile device; determining a pose difference betweenthe first predicted pose and the second predicted pose; generating atleast a portion of an updated image based on the pose difference and atleast a portion of the rendered image; and displaying the at least aportion of the updated image on a display of the mobile device.
 9. Themethod of claim 8, wherein: the second predicted pose corresponds with amiddle display time for displaying the updated image on the mobiledevice.
 10. The method of claim 8, wherein: the generating a renderedimage includes identifying a virtual object being focused on by an enduser of the mobile device, determining a stabilization plane based on alocation of the virtual object within an augmented reality environment,and generating the rendered image based on the stabilization plane. 11.The method of claim 8, wherein: the at least a portion of the updatedimage corresponds with one or more pixel rows within the updated imagepointed to by a rolling buffer.
 12. The method of claim 8, wherein: thegenerating at least a portion of an updated image includes applying ahomographic transformation to the at least a portion of the renderedimage.
 13. The method of claim 12, wherein: the homographictransformation comprises a multi-plane homography.
 14. The method ofclaim 12, wherein: the homographic transformation comprises an affinehomography.
 15. The method of claim 8, wherein: the mobile devicecomprises an HMD.
 16. One or more storage devices containing processorreadable code for programming one or more processors to perform a methodfor displaying images associated with one or more virtual objects usingan HMD comprising the steps of: determining a first predicted poseassociated with the HMD; generating a rendered image based on the firstpredicted pose; determining a second predicted pose associated with theHMD subsequent to the determining a first predicted pose, the secondpredicted pose corresponds with a middle display time for displaying anupdated image on the HMD; determining a pose difference between thefirst predicted pose and the second predicted pose; generating theupdated image based on the pose difference and at least a portion of therendered image; and displaying the updated image using the HMD.
 17. Theone or more storage devices of claim 16, wherein: the generating arendered image includes identifying a virtual object being focused on byan end user of the HMD, determining a stabilization plane based on adistance of the virtual object from the HMD, and generating the renderedimage based on the stabilization plane.
 18. The one or more storagedevices of claim 16, wherein: the generating the updated image includesapplying a homographic transformation to the at least a portion of therendered image.
 19. The one or more storage devices of claim 18,wherein: the homographic transformation comprises a multi-planehomography.
 20. The one or more storage devices of claim 16, wherein:the generating the updated image includes applying a pixel offsetadjustment to the at least a portion of the rendered image.